This invention relates to interconnecting power supplies and more particularly to apparatus for jumpering batteries.
Lead-acid batteries of the type commonly found in automobiles and other vehicles internally generate hydrogen and oxygen gases (at the plates of the batteries) which are highly explosive. Care must be taken to keep flames, sparks, etc. away from such a battery since an explosion resulting from the combustion of these gases may rupture the battery container causing electrolyte (sulphuric acid and water) to be sprayed or spilled over nearby people or objects with potentially harmful consequences. A common situation in which the danger of explosion arises is when a battery in one automobile is jumpered to a discharged battery in another automobile so the latter vehicle may be started. Jumper cables are typically used for jumpering batteries and hook-up procedures have been recommended to reduce the danger of creating sparks at a battery terminal. It has been further recommended that one of the jumper cables have an in-line switch which is open while the cables are being connected and closed only after all connections are made. While such a switch may reduce the danger of sparks being created while a hook-up is made, sparks may occur when the switch itself is closed and opened and these sparks may ignite the gases and cause and explosion.